A　three-dimensional　mathematical　model　of　the　smoke　movement　in　tunnel　fires　was　established.　Finite　volume　method　was　used　to　discretize　the　governing　equations　and　the　SIMPLE　algorithm　was　employed　to　solve　the　governing　equations.　A　scaling　model　(　1:　8)　of　the　subway　tunnel　was　built　up　based　on　similarity　theory.　Not　only　different　positions　of　fire　on　the　train,　but　also　the　different　starting　times　of　exhaust　fan　in　the　tunnel　were　considered.　The　disciplines　of　smoke　temperature,　smoke　diffusion　and　wind　velocity　have　then　been　compared　under　different　the　fire　situations.　The　study　is　useful　to　analyze　evacuating　and　controlling　fire　in　emergent　project　of　tunnel　fire　in　a　subway　system.　(C)　2014　The　Authors.　Published　by　Elsevier　Ltd.